KR20150027874A - Method for preparing levulinic acid using solid acid catalyst under biomass-derived ethylene glycol-based solvent - Google Patents

Abstract

Provided is a method for producing levulinic acid using a solid acid catalyst under an ethylene glycol-based solvent condition. The levulinic acid of the present invention uses a linear or cyclic ethylene glycol-based compound as a solvent, and the levulinic acid can be produced from fructose at a reaction temperature of 100 to 200°C under a solid acid catalyst. Accordingly, dependence on petroleum can be reduced, and greenhouse gas regulations can be dealt with. Moreover, levulinic acid can be obtained from fructose at a high yield, and a solvent and a catalyst can be effectively separated, collected, and re-used after the reaction is finished.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing levulinic acid using a solid acid catalyst in an ethylene glycol-based compound solvent derived from biomass,

The present invention relates to a process for producing levulinic acid, and more particularly, to a process for producing levulinic acid from leukocyte derived from fructose using ethylene glycol-based solvent derived from biomass and solid acid catalyst, which is a platform compound of biofuel or bio- Nitric acid.

Limited oil reserves will inevitably be depleted at some point, and the surge in oil demand due to the growth of emerging economies is creating an imbalance in market supply and demand, leading to an era of high oil prices. Moreover, irreversible greenhouse gases arising from the indiscriminate use of oil are causing serious environmental problems such as global warming.

Already, countries around the world are making efforts to replace petroleum resources through renewable and sustainable biomass. Biofuels such as bioethanol and biodiesel, and bioplastic monomers such as lactic acid and propanediol, To replace transportation fuels or petrochemicals.

As a part of such efforts, recently, a substance which is widely known is levulinic acid obtained from a dehydration reaction of a biomass-derived carbohydrate.

In the dehydration process, levulinic acid should be produced as 5-hydroxymethyl-2-furfural (HMF) in the case of hexose and as furfural in the case of pentose, The carbohydrate compound that is most readily converted into the loxymethyl-2-furfural intermediate is fructose having a pentagonal ring structure.

In the US DOE report, Levinic acid is one of the platform compounds selected as "Top Value Added Chemicals from Biomass" and can be converted to various compounds such as polymeric monomers, herbicides, medicines, spices, solvents, plasticizers, antifreeze, fuel additives [(i) JJ Bozell, GR Petersen, Green Chem. 2010, 12, 539-554; (ii) T. Werpy, G. R. Petersen, Top value added chemicals from biomass volume I - Results of screening for potential candidates from sugars and synthesis gas: U.S. Department of Energy, NREL / TP-510-35523 (2004).], But no industrial mass production has yet been achieved.

Levulinic acid is a compound obtained by dehydration of biomass-derived carbohydrate under acidic conditions. In general, carbohydrates are added to an aqueous solution containing 1-10% of inorganic acid and heated to proceed the reaction. In this case, hydrochloric acid or sulfuric acid is used as the inorganic acid.

However, it is difficult to remove the acid remaining in the solution after the reaction by using the homogeneous inorganic acid as a catalyst, and many problems are involved in the process such as the generation of a large amount of high concentration wastewater. In other words, there is a problem that a large amount of concentrated acidic liquid waste is produced in the production of a product, and the treatment of the concentrated acidic liquid waste liquid takes up a considerable portion of the process cost.

It is an object of the present invention to provide a method for reducing dependence on petroleum and coping with greenhouse gas regulations by using a solvent that can be produced from biomass in a reaction for converting biomass-derived fructose to levulinic acid will be. Also, it is intended to provide a method which can obtain recombinant product from fructose in high yield and efficiently separate the solvent and the catalyst after the reaction is terminated and reuse.

In order to achieve the above-mentioned object of the present invention, there is provided a process for producing an ethylene glycol-based compound, which comprises using a linear or cyclic ethylene glycol-based compound as a solvent, There is provided a process for producing levulinic acid comprising the step of producing levulinic acid from os.

The linear ethylene glycol compound may be a compound represented by the following structural formula (1).

[Structural formula 1]

In the above formula 1,

R ¹ and R ² may be the same or different from each other, R ¹ and R ² are each independently a C 1 to C 6 alkyl group,

m is an integer of 1 to 6;

According to an embodiment of the present invention, preferably,

R ¹ and R ² may be the same or different from each other, R ¹ and R ² are each independently a methyl group or an ethyl group, and m is an integer of 1 to 4.

The cyclic ethylene glycol compound may be a compound represented by the following structural formula (2).

[Structural formula 2]

In the above formula 2,

n is an integer of 1 to 6;

In another embodiment of the present invention, preferably,

and n is an integer of 1 to 3.

The linear or cyclic ethylene glycol compound may be prepared from ethanol obtained by fermentation of biomass.

Wherein the linear or cyclic ethylene glycol compound is selected from the group consisting of 1,4-dioxane, monoethylene glycol dimethyl ether, diethylene glycol dimethyl ether, Triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. These solvents may be used alone or in combination of two or more.

Wherein the fructose is provided in the form of a syrup containing the fructose and water and the content of water is 10 to 50 parts by weight based on 100 parts by weight of the fructose, Weight portion.

The solid acid catalyst may be in the form of a Bronsted acid or Lewis acid functional group linked to an organic or inorganic support.

The organic support may include at least one selected from the group consisting of polystyrene, polyamide and polyethylene glycol.

The inorganic support may include at least one selected from silica, alumina and zeolite.

The solid acid catalyst may be one in which a sulfonic acid group is introduced into an amorphous carbon formed by incomplete carbonization of biomass.

The reaction temperature may be more preferably 120 to 180 ° C.

And separating the solvent and the solid acid catalyst from each other after the step of producing levulinic acid to reuse the solid acid catalyst.

The process for producing levulinic acid of the present invention can reduce the dependency of petroleum in the chemical industry and can respond to greenhouse gas regulations by using a solvent that can be derived from biomass. In addition, levulinic acid, which is a product from fructose, can be obtained in high yield, and after the reaction is completed, the solvent and the catalyst can be efficiently separated and reused by simple filtration.

Fig. 1 shows changes in HPLC chromatograms in the process of preparing levulinic acid according to Example 5. Fig.

Hereinafter, embodiments and examples of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention.

It is to be understood, however, that the following description is not intended to limit the invention to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises ", or" having ", and the like, specify that the presence of stated features, integers, steps, operations, elements, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

As used herein, unless otherwise defined, the term "alkyl group" means a straight, branched or cyclic aliphatic hydrocarbon group. The alkyl group may be a "saturated alkyl group" which does not contain any double or triple bonds.

The alkyl group may be an "unsaturated alkyl group" comprising at least one double bond or triple bond.

The alkyl group may be a C1 to C6 alkyl group, preferably a C1 to C3 alkyl group.

For example, the C1 to C4 alkyl groups may have 1 to 4 carbon atoms in the alkyl chain, i.e., the alkyl chain may be optionally substituted with one or more substituents selected from the group consisting of methyl, ethyl, propyl, iso-propyl, n-butyl, Indicating that they are selected from the group.

Specific examples of the alkyl group include a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, ethenyl group, Butyl group, cyclopentyl group, cyclohexyl group, and the like.

The method for producing levulinic acid according to the present invention can produce levulinic acid by using a solid acid catalyst in a linear or cyclic ethylene glycol compound solvent and dehydroxylating fructose at a reaction temperature of 100 to 200 ° C have.

The mechanism of the production of levulinic acid from fructose according to the dehydration reaction is as shown in the following reaction formula (1).

[Reaction Scheme 1]

The intermediate compounds of Scheme 1 react with the fructopyranose pathway, which acts as a reversible fructose reservoir when fructose is converted to levulinic acid and is converted to undesired byproducts such as humin Can be prevented.

The above-mentioned linear or cyclic ethylene glycol-based compound solvent helps to stabilize such an intermediate compound, and thus makes it possible to obtain levulinic acid from fructose in high yield.

In the dehydration reaction, the reaction temperature is preferably 100 to 200 ° C. More preferably 120 to 180 ° C.

 When the reaction temperature is 100 ° C or lower, the reaction rate is slowed to lower the conversion of the intermediate 5-hydroxymethyl-2-furfural to levulinic acid, thereby lowering the yield. When the reaction temperature is 200 ° C or higher, .

The reaction time may vary depending on the reaction temperature. The reaction time is long when the reaction temperature is low, and the reaction time is relatively short when the reaction temperature is high. Specifically, when the reaction temperature is 150 ° C, the reaction time may be 0.5 to 15 hours, preferably 2 to 10 hours. When the reaction temperature is lower than 150 ° C, the reaction time is relatively long, and when the reaction temperature is higher than 150 ° C, the reaction time can be relatively short.

The reaction pressure can be easily and economically advantageous because the reaction can proceed at atmospheric pressure at the reaction temperature below the boiling point of the reaction solvent. Since the pressure in the reactor increases due to the vapor pressure at the reaction temperature higher than the boiling point of the reaction solvent, a reaction device capable of withstanding the pressurized condition is required, but the reaction time can be reduced as described above. Therefore, the reaction pressure and the reaction temperature can be appropriately adjusted according to the situation.

The linear ethylene glycol-based compound solvent may be a compound represented by the following structural formula (1).

[Structural formula 1]

In the above formula 1,

R ¹ and R ² may be the same or different from each other, R ¹ and R ² are each independently a C 1 to C 6 alkyl group,

m is an integer of 1 to 6;

As shown in the structural formula 1, the linear ethylene glycol compound solvent may be repeated as a unit molecule, and the terminal hydroxyl group may have a molecular structure protected in an alkyl ether form.

The number of repeating units (m) of ethylene glycol may be 1 to 6, preferably 1 to 4. If m is larger than 6, the yield of levulinic acid may be lowered, and after the reaction is completed, separation of the solvent is difficult and reuse may not be possible.

In addition, when the number of carbon atoms of the alkyl group (R ¹ and R ² ) is increased, the hydrophobicity is increased and the compatibility with fructose is lowered so that the yield of levulinic acid can be lowered.

R ¹ and R ² may be the same or different from each other, and R ¹ and R ² are each independently a C ¹ to C 6 alkyl group, more preferably, R ¹ and R ² may be the same or different from each other, and R ¹ and R ² each independently may be a methyl group or an ethyl group.

The cyclic ethylene glycol compound solvent may be a compound represented by the following structural formula (2).

[Structural formula 2]

In the above formula 2,

n is an integer of 1 to 6;

The cyclic ethylene glycol compound solvent may be a cyclic molecular structure in which ethylene glycol is repeated as a unit molecule, as shown in the structural formula (2).

The repeating number (n) of ethylene glycol is preferably 1 to 6, more preferably 1 to 3. When n is 6 or more, it may be chemically unstable to be used as a solvent in an acid catalyst condition.

The linear or cyclic ethylene glycol-based compound solvent can be prepared from ethanol obtained by fermentation of biomass. The schematic mechanism of the production of the ethylene glycol-based compound solvent is shown in the following reaction formula (2).

[Reaction Scheme 2]

Thus, since the ethylene glycol-based compound solvent can be produced from industrially produced bio-ethanol, the manufacturing cost can be reduced and the dependence on the oil can be reduced.

The linear or cyclic biomass-derived ethylene glycol-based compound solvent may be 1,4-dioxane, monoethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and the like.

The solid acid catalyst may be one in which a Bronsted acid or a Lewis acid functional group is connected to an organic or inorganic support.

The organic support may be a polymeric support including polystyrene, polyamide, polyethylene glycol, etc., and the inorganic support may be an inorganic material including silica, alumina, zeolite, and the like.

The functional group linked chemically on such a support may be a Lewis acid comprising a Bronsted acid including a sulfonic acid group, a phosphoric acid group, or the like, or a metal ion coordinated to a ligand.

Here, Bronsted acid is an acid as defined by Bronsted-Lowry, which means a substance capable of giving a proton (H ⁺ ) to another substance in an acid base reaction. Also, Lewis acid means an acid according to the definition of Lewis Lewis, which can be provided with an electron pair in an acid base reaction.

In addition, the solid acid catalyst may be prepared by introducing a sulfonic acid group into an amorphous carbon formed by incomplete carbonization of biomass.

In detail, the amorphous carbon can be produced by incomplete carbonization of biomass, and the biomass can be woody biomass such as wood, rice straw, but is not limited thereto. Preferably, the woody biomass may contain 10 to 40 wt% of a lignin component.

The incomplete carbonization can be performed by a chemical treatment or a heat treatment using a dehydrating agent. The incomplete carbonization by the heat treatment is preferably performed at 400 to 600 ° C.

Thereafter, a sulfonic acid group can be introduced by adding sulfuric acid containing anhydrous sulfuric acid (SO ₃ ) to the amorphous carbon. The sulfuric acid preferably contains 15 to 50 wt% of anhydrous sulfuric acid.

The amorphous carbon type solid acid catalyst having sulfonate groups thus prepared may contain 0.4 to 0.8 mmol of a sulfonic acid group per gram of the amorphous carbon.

The fructose is preferably used in the form of a syrup containing water and fructose.

At this time, the water content is preferably 10 to 50 parts by weight, more preferably 20 to 30 parts by weight, based on 100 parts by weight of fructose.

Since the ethylene glycol-based compound solvent used in the present invention can be completely mixed with water, it is not necessary to use fructose in powder form, and it can be used in a form mixed with water. Therefore, no separate fructose drying process is required.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided to further understand the present invention, and the present invention is not limited by the examples.

[Example]

Example  One

(150 mmol, weight ratio of water: 25%) in the form of a syrup and Amberlyst-15 as a solid acid catalyst in a 38 mL-thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap. (300 mg), and the reaction was carried out using an EG-based solvent, monoethylene glycol dimethyl ether (3 mL). The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 7 hours. After completion of the reaction, the reaction mixture was cooled at room temperature, diluted 100 times with distilled water and subjected to HPLC analysis. As a result, 43% of levulinic acid was produced.

Example  2

(150 mmol, weight ratio of water: 25%) in the form of a syrup and Amberlyst-15 as a solid acid catalyst in a 38 mL-thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap. (300 mg), and the reaction was carried out using an EG-based solvent, diethylene glycol dimethyl ether (3 mL). The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 4 hours. After completion of the reaction, the reaction mixture was cooled at room temperature, diluted 100 times with distilled water and subjected to HPLC analysis. As a result, it was confirmed that 62% of levulinic acid was produced.

Example  3

(150 mmol, weight ratio of water: 25%) in the form of a syrup and Amberlyst-15 as a solid acid catalyst in a 38 mL-thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap. (300 mg), and the reaction was carried out using an EG-based solvent, triethylene glycol dimethyl ether (3 mL). The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 3 hours. After completion of the reaction, the reaction mixture was cooled at room temperature, diluted 100 times with distilled water and subjected to HPLC analysis. As a result, it was confirmed that 56% of levulinic acid was produced.

Example  4

(150 mmol, weight ratio of water: 25%) in the form of a syrup and Amberlyst-15 as a solid acid catalyst in a 38 mL-thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap. (300 mg), and the reaction was carried out using an EG-based solvent, tetraethylene glycol dimethyl ether (3 mL). The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 3 hours. After completion of the reaction, the reaction mixture was cooled at room temperature, diluted 100 times with distilled water, and subjected to HPLC analysis. As a result, 51% of levulinic acid was produced.

Example  5

(150 mmol, weight ratio of water: 25%) in the form of a syrup and Amberlyst-15 as a solid acid catalyst in a 38 mL-thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap. (300 mg), and the reaction was carried out using 1,4-dioxane (3 mL) as an EG-based solvent. The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 3 hours. After completion of the reaction, the reaction mixture was cooled at room temperature, diluted 100 times with distilled water and subjected to HPLC analysis. As a result, it was confirmed that 71% of levulinic acid was produced.

Example  6

An amorphous carbon material into which a sulfonic acid group was introduced as a solid acid catalyst was prepared and prepared.

Specifically, 10 g of wood flour was placed in a 500 ml round bottom flask, and 100 g of [EMIM] Cl was added. The mixture was heated to 120 < 0 > C and stirred at 650 rpm. The homogenous mixture was cooled to < RTI ID = 0.0 > 10 C < / RTI > The precipitate was filtered, washed with water and dried under vacuum. Thereafter, the amorphous carbon material was prepared by heating at 500 DEG C for 1 hour in a nitrogen atmosphere.

The amorphous carbon material is conc. H ₂ SO ₄ (10%, wt / vol) and stirred at 80 ° C for 2 hours. Subsequently, it was cooled, filtered, washed with hot water, further washed with 1,4-dioxane by means of a Soxhilet apparatus and vacuum dried to produce amorphous carbon material with sulfonic acid groups introduced.

(150 mmol, weight ratio of water: 25%) in the form of a syrup to a 38 mL thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap, The amorphous carbon material (900 mg) derived from the biomass was introduced and the reaction was carried out using an EG-based solvent such as diethylene glycol dimethyl ether (3 mL). The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 10 hours. After completion of the reaction, the reaction mixture was cooled at room temperature, diluted 100 times with distilled water and subjected to HPLC analysis. As a result, it was confirmed that 55% of levulinic acid was produced.

Example  7

After preparing levulinic acid according to Example 2, the product was cooled to room temperature, and Amberlyst-15 was filtered, washed and vacuum dried to recover Amberlyst-15, and diethylene glycol dimethyl ether was separated and recovered by distillation.

The separated and recovered Amberlyst-15 and diethylene glycol dimethyl ether were used to prepare levulinic acid in the same manner as in Example 2. After completion of the reaction, the reaction mixture was diluted 100 times with distilled water and subjected to HPLC analysis. As a result, it was confirmed that 61% of levulinic acid was produced.

Comparative Example  One

(150 mmol, weight ratio of water: 25%) in the form of a syrup and Amberlyst-15 as a solid acid catalyst in a 38 mL-thick glass walled pressure tubular reactor (25.5 mm of OD and 20.3 cm of length) equipped with a Teflon screw cap. (300 mg), and the reaction was carried out using 1,3-dioxane (3 mL) having a chemical structure similar to that of EG-based solvent. The reaction mixture was heated to 150 < 0 > C and stirred at 700 rpm for 3 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, diluted 100 times with distilled water and analyzed by HPLC. As a result, it was confirmed that 1,3-dioxane as a solvent was decomposed under acidic reaction conditions.

The production conditions and yields of levulinic acid in Examples 1 to 7 and Comparative Example 1 are summarized in Table 1 below.

division menstruum catalyst Reaction temperature (캜) Reaction time (h) Yield of levulinic acid (%) Example 1 monoethylene glycol dimethyl ether Amberlyst-15 150 7 43 Example 2 diethylene glycol dimethyl ether Amberlyst-15 150 4 62 Example 3 triethylene glycol dimethyl ether Amberlyst-15 150 3 56 Example 4 tetraethylene glycol dimethyl ether Amberlyst-15 150 3 51 Example 5 1,4-dioxane Amberlyst-15 150 3 71 Example 6 diethylene glycol dimethyl ether Amorphous carbon introduced with a sulfonic group 150 10 55 Example 7 diethylene glycol dimethyl ether Amberlyst-15
(Number of separation) 150 4 61 Comparative Example 1 1,3-dioxane Amberlyst-15 150 3 0

According to the above Table 1, Examples 1 to 7 of the present invention show that the yield of levulinic acid is very high as compared with Comparative Example 1 in which an ethylene glycol-based solvent derived from biomass is not used.

Test Example  One: HPLC ( High Performance Liquid Chromatography ) analysis

The changes in HPLC chromatogram at the reaction intermediate point (a) and the reaction termination point (b) in Example 5 of the present invention are shown in Fig.

According to FIG. 1, when 1,4-dioxane, which is an ethylene glycol-based compound solvent derived from biomass, was used, it was confirmed that many intermediate compounds were produced and disappeared during the reaction. The above-mentioned intermediate compounds have the function of blocking the pathway of conversion of fructose to by-product when converted to levulinic acid, as described in the description of the dehydration reaction mechanism.

In addition, it was confirmed that the product prepared according to Example 5 was a levulinic acid through comparison with an authentic sample on HPLC at the end of the reaction.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (14)

The step of preparing levulinic acid from fructose at a reaction temperature of 100 to 200 DEG C under a solid acid catalyst using a linear or cyclic ethylene glycol-based compound as a solvent / RTI > acid. The method according to claim 1,
Wherein the linear ethylene glycol compound is a compound represented by the following structural formula (1).
[Structural formula 1]

In the above formula 1,
R ¹ and R ² may be the same or different from each other, R ¹ and R ² are each independently a C 1 to C 6 alkyl group,
m is an integer of 1 to 6; 3. The method of claim 2,
R ¹ and R ² may be the same or different from each other, R ¹ and R ² are each independently a methyl group or an ethyl group, and m is an integer of from 1 to 4. 2. A process for producing levulinic acid, The method according to claim 1,
Wherein the cyclic ethylene glycol compound is a compound represented by the following structural formula (2).
[Structural formula 2]

In the above formula 2,
n is an integer of 1 to 6; 5. The method of claim 4,
and n is an integer of 1 to 3. < Desc / Clms Page number 36 > The method according to claim 1,
Wherein said linear or cyclic ethylene glycol compound is prepared from ethanol obtained by fermentation of biomass. The method according to claim 1,
Wherein the linear or cyclic ethylene glycol compound is selected from the group consisting of 1,4-dioxane, monoethylene glycol dimethyl ether, diethylene glycol dimethyl ether, Wherein the solvent is at least one selected from the group consisting of triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. The method according to claim 1,
In the step of producing levulinic acid, the fructose is provided in the form of a syrup containing the fructose and water, and the content of the water is 10 to 50 parts by weight, based on 100 parts by weight of the fructose. By weight, based on the total weight of the polylactic acid. The method according to claim 1,
Wherein the solid acid catalyst is in the form of a Bronsted acid or Lewis acid functional group linked to the organic or inorganic support. 10. The method of claim 9,
Wherein the organic support comprises at least one selected from the group consisting of polystyrene, polyamide, and polyethylene glycol. 10. The method of claim 9,
Wherein the inorganic support comprises at least one selected from silica, alumina and zeolite. The method according to claim 1,
Wherein the solid acid catalyst comprises a sulfonic acid group introduced into an amorphous carbon formed by incomplete carbonization of biomass. The method according to claim 1,
Wherein the reaction temperature is from 120 to 180 占 폚. The method according to claim 1,
Further comprising separating the solvent and the solid acid catalyst from each other after the step of producing levlinic acid to reuse the solid acid catalyst.

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